Cap for a water bottle



FIG. 1 is a perspective view showing the front, top and left sides of a cap for a water bottle embodying our new design;

FIG. 2 is a front elevation view thereof, the rear elevation view being identical to the front view as shown;

FIG. 3 is a right side elevation view thereof, the left side elevation view being identical to the right side as shown;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a cap for a water bottle, as shown and described. 